My grandparents always had plants that look slightly like the top of those and they called them "roosters and hens" or "hens and chicks" or something, but they never grew so long.

That is called Serpents Spine ( yeah, nice). Your are correct in calling it sedum, it is in the Succulents family.

Use gloves when you touch that. I have it in my garden and it is lovely, but if I get any of the sap on my skin, I get really bad irritation.

I used to have to boil milkweed three times to remove the latex. Pencil actually also has an irritating sap.

I don't know why I even tried growing pencil cactus. They are ugly.

They are both Euphorbia.